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  • Why is setting HTML5's CanvasPixelArray values is ridiculously slow and how can I do it faster?

    - by Nixuz
    I am trying to do some dynamic visual effects using the HTML 5 canvas' pixel manipulation, but I am running into a problem where setting pixels in the CanvasPixelArray is ridiculously slow. For example if I have code like: imageData = ctx.getImageData(0, 0, 500, 500); for (var i = 0; i < imageData.length; i += 4){ imageData.data[index] = buffer[i]; imageData.data[index + 1] = buffer[i]; imageData.data[index + 2] = buffer[i]; } ctx.putImageData(imageData, 0, 0); Profiling with Chrome reveals, it runs 44% slower than the following code where CanvasPixelArray is not used. tempArray = new Array(500 * 500 * 4); imageData = ctx.getImageData(0, 0, 500, 500); for (var i = 0; i < imageData.length; i += 4){ tempArray[index] = buffer[i]; tempArray[index + 1] = buffer[i]; tempArray[index + 2] = buffer[i]; } ctx.putImageData(imageData, 0, 0); My guess is that the reason for this slowdown is due to the conversion between the Javascript doubles and the internal unsigned 8bit integers, used by the CanvasPixelArray. Is this guess correct? Is there anyway to reduce the time spent setting values in the CanvasPixelArray?

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  • SQL Server full text query across multiple tables - why so slow?

    - by Mikey Cee
    Hi. I'm trying to understand the performance of an SQL Server 2008 full-text query I am constructing. The following query, using a full-text index, returns the correct results immediately: SELECT O.ID, O.Name FROM dbo.EventOccurrence O WHERE FREETEXT(O.Name, 'query') ie, all EventOccurrences with the word 'query' in their name. And the following query, using a full-text index from a different table, also returns straight away: SELECT V.ID, V.Name FROM dbo.Venue V WHERE FREETEXT(V.Name, 'query') ie. all Venues with the word 'query' in their name. But if I try to join the tables and do both full-text queries at once, it 12 seconds to return: SELECT O.ID, O.Name FROM dbo.EventOccurrence O INNER JOIN dbo.Event E ON O.EventID = E.ID INNER JOIN dbo.Venue V ON E.VenueID = V.ID WHERE FREETEXT(E.Name, 'search') OR FREETEXT(V.Name, 'search') Here is the execution plan: http://uploadpad.com/files/query.PNG From my reading, I didn't think it was even possible to make a free text query across multiple tables in this way, so I'm not sure I am understanding this correctly. Note that if I remove the WHERE clause from this last query then it returns all results within a second, so it's definitely the full-text that is causing the issue here. Can someone explain (i) why this is so slow and (ii) if this is even supported / if I am even understanding this correctly. Thanks in advance for your help.

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  • Ruby: Why is Array.sort slow for large objects?

    - by David Waller
    A colleague needed to sort an array of ActiveRecord objects in a Rails app. He tried the obvious Array.sort! but it seemed surprisingly slow, taking 32s for an array of 3700 objects. So just in case it was these big fat objects slowing things down, he reimplemented the sort by sorting an array of small objects, then reordering the original array of ActiveRecord objects to match - as shown in the code below. Tada! The sort now takes 700ms. That really surprised me. Does Ruby's sort method end up copying objects about the place rather than just references? He's using Ruby 1.8.6/7. def self.sort_events(events) event_sorters = Array.new(events.length) {|i| EventSorter.new(i, events[i])} event_sorters.sort! event_sorters.collect {|es| events[es.index]} end private # Class used by sort_events class EventSorter attr_reader :sqn attr_reader :time attr_reader :index def initialize(index, event) @index = index @sqn = event.sqn @time = event.time end def <=>(b) @time != b.time ? @time <=> b.time : @sqn <=> b.sqn end end

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  • Searching with a UISearchbar is slow and blocking the main thread.

    - by Robert
    I have a Table with over 3000 entries and searching is very slow. At the moment I am doing just like in the 'TableSearch' example code (but without scopes) - (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString { [self filterContentForSearchText: searchString]; // Return YES to cause the search result table view to be reloaded. return YES; } And the filterContentForSearchText method is as follows: - (void) filterContentForSearchText:(NSString*)searchText { // Update the filtered array based on the search text // First clear the filtered array. [filteredListContent removeAllObjects]; // Search the main list whose name matches searchText // add items that match to the filtered array. if (fetchedResultsController.fetchedObjects) { for (id object in fetchedResultsController.fetchedObjects) { NSString* searchTarget = [tableTypeDelegate getStringForSearchFilteringFromObject:object]; if ([searchTarget rangeOfString:searchText options:(NSCaseInsensitiveSearch|NSDiacriticInsensitiveSearch)].location != NSNotFound) { [filteredListContent addObject:object]; } } } } My question is twofold: How do can I make the searching process faster? How can I stop the search from blocking the main thread? i.e. stop it preventing the user from typing more characters. For the second part, I tried "performSelector:withObject:afterDelay:" and "cancelPreviousPerformRequests..." without much success. I suspect that I will need to use threading instead, but I do not have much experience with it.

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  • [C#] Three System.Drawing methods manifest slow drawing or flickery: Solutions? or Other Options?

    - by Luke Mcneice
    Hi all, I am doing a little graphing via the System.Drawing and im having a few problems. I'm holding data in a Queue and i'm drawing(graphing) out that data onto three picture boxes this method fills the picture box then scrolls the graph across. so not to draw on top of the previous drawings (and graduly looking messier) i found 2 solutions to draw the graph. Call plot.Clear(BACKGOUNDCOLOR) before the draw loop [block commented] although this causes a flicker to appear from the time it takes to do the actual drawing loop. call plot.DrawLine(channelPen[5], j, 140, j, 0); just before each drawline [commented] although this causes the drawing to start ok then slow down very quickly to a crawl as if a wait command had been placed before the draw command. Here is the Code for reference: /*plotx.Clear(BACKGOUNDCOLOR) ploty.Clear(BACKGOUNDCOLOR) plotz.Clear(BACKGOUNDCOLOR)*/ for (int j = 1; j < 599; j++) { if (j > RealTimeBuffer.Count - 1) break; QueueEntity past = RealTimeBuffer.ElementAt(j - 1); QueueEntity current = RealTimeBuffer.ElementAt(j); if (j == 1) { //plotx.DrawLine(channelPen[5], 0, 140, 0, 0); //ploty.DrawLine(channelPen[5], 0, 140, 0, 0); //plotz.DrawLine(channelPen[5], 0, 140, 0, 0); } //plotx.DrawLine(channelPen[5], j, 140, j, 0); plotx.DrawLine(channelPen[0], j - 1, (((past.accdata.X - 0x7FFF) / 256) + 64), j, (((current.accdata.X - 0x7FFF) / 256) + 64)); //ploty.DrawLine(channelPen[5], j, 140, j, 0); ploty.DrawLine(channelPen[1], j - 1, (((past.accdata.Y - 0x7FFF) / 256) + 64), j, (((current.accdata.Y - 0x7FFF) / 256) + 64)); //plotz.DrawLine(markerPen, j, 140, j, 0); plotz.DrawLine(channelPen[2], j - 1, (((past.accdata.Z - 0x7FFF) / 256) + 94), j, (((current.accdata.Z - 0x7FFF) / 256) + 94)); } Is there any tricks to avoid these overheads? If not would there be any other/better solutions?

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  • [C#] Two System.Drawing methods manifest slow drawing or flickery: Solutions? or Other Options?

    - by Luke Mcneice
    Hi all, I am doing a little graphing via the System.Drawing and im having a few problems. I'm holding data in a Queue and i'm drawing(graphing) out that data onto three picture boxes this method fills the picture box then scrolls the graph across. so not to draw on top of the previous drawings (and graduly looking messier) i found 2 solutions to draw the graph. Call plot.Clear(BACKGOUNDCOLOR) before the draw loop [block commented] although this causes a flicker to appear from the time it takes to do the actual drawing loop. call plot.DrawLine(channelPen[5], j, 140, j, 0); just before each drawline [commented] although this causes the drawing to start ok then slow down very quickly to a crawl as if a wait command had been placed before the draw command. Here is the Code for reference: /*plotx.Clear(BACKGOUNDCOLOR) ploty.Clear(BACKGOUNDCOLOR) plotz.Clear(BACKGOUNDCOLOR)*/ for (int j = 1; j < 599; j++) { if (j > RealTimeBuffer.Count - 1) break; QueueEntity past = RealTimeBuffer.ElementAt(j - 1); QueueEntity current = RealTimeBuffer.ElementAt(j); if (j == 1) { //plotx.DrawLine(channelPen[5], 0, 140, 0, 0); //ploty.DrawLine(channelPen[5], 0, 140, 0, 0); //plotz.DrawLine(channelPen[5], 0, 140, 0, 0); } //plotx.DrawLine(channelPen[5], j, 140, j, 0); plotx.DrawLine(channelPen[0], j - 1, (((past.accdata.X - 0x7FFF) / 256) + 64), j, (((current.accdata.X - 0x7FFF) / 256) + 64)); //ploty.DrawLine(channelPen[5], j, 140, j, 0); ploty.DrawLine(channelPen[1], j - 1, (((past.accdata.Y - 0x7FFF) / 256) + 64), j, (((current.accdata.Y - 0x7FFF) / 256) + 64)); //plotz.DrawLine(markerPen, j, 140, j, 0); plotz.DrawLine(channelPen[2], j - 1, (((past.accdata.Z - 0x7FFF) / 256) + 94), j, (((current.accdata.Z - 0x7FFF) / 256) + 94)); } Is there any tricks to avoid these overheads? If not would there be any other/better solutions?

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  • Why is my django bulk database population so slow and frequently failing?

    - by bryn
    I decided I'd like to use django's model system rather than coding raw SQL to interface with my database, but I am having a problem that surely is avoidable. My models.py contains: class Student(models.Model): student_id = models.IntegerField(unique = True) form = models.CharField(max_length = 10) preferred = models.CharField(max_length = 70) surname = models.CharField(max_length = 70) and I'm populating it by looping through a list as follows: from models import Student for id, frm, pref, sname in large_list_of_data: s = Student(student_id = id, form = frm, preferred = pref, surname = sname) s.save() I don't really want to be saving this to the database each time but I don't know another way to get django to not forget about it (I'd rather add all the rows and then do a single commit). There are two problems with the code as it stands. It's slow -- about 20 students get updated each second. It doesn't even make it through large_list_of_data, instead throwing a DatabaseError saying "unable to open database file". (Possibly because I'm using sqlite3.) My question is: How can I stop these two things from happening? I'm guessing that the root of both problems is that I've got the s.save() but I don't see a way of easily batching the students up and then saving them in one commit to the database.

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  • Slow loading of UITableView. How know why?

    - by mamcx
    I have a UITableView that show a long list of data. Use sections and follow the sugestion of http://stackoverflow.com/questions/695814/how-solve-slow-scrolling-in-uitableview . The flow is load a main UITableView & push a second selecting a row from there. However, with 3000 items take 11 seconds to show. I suspect first from the load of the records from sqlite (I preload the first 200). So I cut it to only 50. However, no matter if I preload only 1 or 500, the time is the same. The view is made from IB and all is opaque. I run out of ideas in how detect the problem. I run the Instruments tool but not know what to look. Also, when the user select a cell from the previous UITable, no visual feedback is show (ie: the cell not turn selected) for a while so he thinks he not select it and try several times. Is related to this problem. What to do? NOTE: The problem is only in the actual device: iPod Touch 2d generation Using fmdb as sqlite api Doing the caching in viewDidLoad Using NSDictionary for the caching Using a NSAutoreleasePool for the caching part. Only caching the row ID & mac 4 fields necesary to show the cell data UIView made with interface builder, SDK 2.2.1 Instruments say I use 2.5 MB in the device

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  • Why does Mass Effect 1 run so slow on my machine if I have an XFX NVidia 9400GT video card? [closed]

    - by Papuccino1
    I so sick and tired of having my components pass the minimum requirements of a game and then I get 15 FPS on the game on everything low. Should't PC developers say 'use at least this video card for a smooth 30 FPS'? Here are my specs: Windows 7 2GB DDR2 RAM XFX Nvidia 9400gt Intel Pentium D Dual Core 2.8ghz I should be at LEAST getting 30 FPS on everything low right? Please tell me what I can do to make games run as they should, or is my video card not good for these games? Here are the recommended requirements from the official site: Recommended System Requirements for Mass Effect on the PC Operating System: Windows XP or Vista Processor: 2.6+GHZ Intel or 2.4+GHZ AMD Memory: 2 Gigabyte Ram Video Card: NVIDIA GeForce 7900 GTX or higher. ATI X1800 XL series or higher Hard Drive Space: 12 Gigabytes Sound Card: DirectX 9.0c compatible sound card and drivers – 5.1 sound card recommended My videocard is 9400GT, how is that worse than a 7900GTX? :S Edit 2: I should note, that I get poor frames when running the game in absolute BOTTOM specs. lowest resolution, no particles, etc. etc. Absolute ZERO and getting poor framerates.

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  • Ldap ssh authentication is super slow... any way to speed it up?

    - by Johnathon
    I am running OpenSUSE. Here is the output of ssh -vvv: OpenSSH_5.8p1, OpenSSL 1.0.0c 2 Dec 2010 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to <ipaddress> [ipaddress] port 22. debug1: Connection established. debug1: permanently_set_uid: 0/0 debug3: Incorrect RSA1 identifier debug3: Could not load "/root/.ssh/id_rsa" as a RSA1 public key debug2: key_type_from_name: unknown key type '-----BEGIN' debug3: key_read: missing keytype debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug2: key_type_from_name: unknown key type '-----END' debug3: key_read: missing keytype debug1: identity file /root/.ssh/id_rsa type 1 debug1: identity file /root/.ssh/id_rsa-cert type -1 debug1: identity file /root/.ssh/id_dsa type -1 debug1: identity file /root/.ssh/id_dsa-cert type -1 debug1: identity file /root/.ssh/id_ecdsa type -1 debug1: identity file /root/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.1 debug1: match: OpenSSH_5.1 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.8 debug2: fd 3 setting O_NONBLOCK debug3: load_hostkeys: loading entries for host "ipaddress" from file "/root/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /root/.ssh/known_hosts:4 debug3: load_hostkeys: loaded 1 keys debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],ssh-rsa debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: [email protected],[email protected],ssh-rsa,[email protected],[email protected],[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug2: dh_gen_key: priv key bits set: 138/256 debug2: bits set: 529/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Server host key: RSA cb:7f:ff:2e:65:28:f0:95:e6:8a:71:24:2a:67:02:2b debug3: load_hostkeys: loading entries for host "<ipaddress>" from file "/root/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /root/.ssh/known_hosts:4 debug3: load_hostkeys: loaded 1 keys debug1: Host '<ipaddress>' is known and matches the RSA host key. debug1: Found key in /root/.ssh/known_hosts:4 debug2: bits set: 504/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /root/.ssh/id_rsa (0xb789d5c8) debug2: key: /root/.ssh/id_dsa ((nil)) debug2: key: /root/.ssh/id_ecdsa ((nil)) debug1: Authentications that can continue: publickey,keyboard-interactive debug3: start over, passed a different list publickey,keyboard-interactive debug3: preferred publickey,keyboard-interactive,password debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Offering RSA public key: /root/.ssh/id_rsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply It hangs here for a good 30 seconds to a minute then debug1: Authentications that can continue: publickey,keyboard-interactive debug1: Trying private key: /root/.ssh/id_dsa debug3: no such identity: /root/.ssh/id_dsa debug1: Trying private key: /root/.ssh/id_ecdsa debug3: no such identity: /root/.ssh/id_ecdsa debug2: we did not send a packet, disable method debug3: authmethod_lookup keyboard-interactive debug3: remaining preferred: password debug3: authmethod_is_enabled keyboard-interactive debug1: Next authentication method: keyboard-interactive debug2: userauth_kbdint debug2: we sent a keyboard-interactive packet, wait for reply debug2: input_userauth_info_req debug2: input_userauth_info_req: num_prompts 1 I added PubkeyAuthentication no to the /etc/ssh/ssh_config and the /etc/ssh/sshd_config which makes it faster getting to the password prompt, but the password prompt still takes some time. Any way to fix that? Here is where the password hangs debug3: packet_send2: adding 32 (len 25 padlen 7 extra_pad 64) debug2: input_userauth_info_req debug2: input_userauth_info_req: num_prompts 0 debug3: packet_send2: adding 48 (len 10 padlen 6 extra_pad 64) debug1: Authentication succeeded (keyboard-interactive). Authenticated to ipaddress ([ipaddress]:22). debug1: channel 0: new [client-session] debug3: ssh_session2_open: channel_new: 0 debug2: channel 0: send open debug1: Requesting [email protected] debug1: Entering interactive session. FIXED!!!!!!!!!!!!!! What is did... In the nsswitch_conf I had ldap included in the group and passwd which slows it down a lot. Thank you everybody for your input passwd: compat group: files hosts: files dns networks: files dns

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  • Why is lassoing ink in OneNote so slow in general? Doesn't anyone care?

    - by GuoLiang Oon
    Now I understand that this is especially an (known) issue in the OneNote 2013 preview and that it will probably be fixed in the final release. But lassoing in OneNote 2010 was no sprightly affair either. I'm just perplexed really, why on earth is there such an issue? Is lassoing intrinsically computationally expensive? OneNote would be soooooooooooo much more useful if there's no lasso lag. And doing a laggy lasso on tablet pcs with weak processors is just so much worse. Or do most folks just don't use the lasso feature much? I use it primarily to shrink intermediate calculations for future retrieval.

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  • Why does a wired network slow down with user increase?

    - by Ed Briscoe
    If you had a wired network, 20 PCs hooked up to a 100 Mbit/sec switch (same onboard ethernet port speed) and you were just sending some test data round. What is the technical explanation as to why 20 machines sending test data around this network to each other is slower than one to one? I mean I know a busy network means it's slower but I'm really trying to understand some more technical details. Thanks for any help

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  • fail2ban log parsing too slow on Raspberry Pi - options? [migrated]

    - by Gordon Morehouse
    I'm running fail2ban on a Raspberry Pi at 950MHz which I cannot overclock further. The Pi is occasionally subject to SYN floods on particular ports. I've set up iptables to throttle the rate of SYNs on the port of interest; when the throttle limits are exceeded, hosts which send SYNs are dropped into the REJECT chain and the particular SYN packet which exceeded the limit is logged. fail2ban then watches for these logged SYNs and, after seeing a few, temporarily bans the host for a short time (this is a transient issue in the app I'm working with). The problem is that the SYN floods can occasionally reach rates which are too fast for fail2ban to keep up with; I'll see 20-40 log messages per second, and eventually fail2ban falls behind and becomes ineffective. To add insult to injury, it continues consuming a LOT of CPU as it tries to catch up. I have verified that DROP chained packets from hosts already banned by fail2ban are not logged, and thus do not add to its load. What are my options here? I have a few ideas, but no clear path forward. Could I make the log-parse regex "easier" so it takes fewer cycles? Would using iptables --log-prefix to put a token near the start of the log message, and/or otherwise simplifying/altering the fail2ban regex help? Here is the current fail2ban config line containing a regex: failregex = kernel:.*?SRC=(?:::f{4,6}:)?(?P<host>[\w\-.^_]+) DST.*?SYN Is there a faster way for fail2ban to watch for the packets exceeding the limits than parsing kern.log? Could fail2ban be run under PyPy instead of CPython with minimal nonstandard wizardry (the OS is Raspbian 7, so, mostly Debian 7)? Is there something better than fail2ban that I could use to watch for the packets which exceed the SYN limits, and after N exceeds in X seconds, temporarily put the offending IP into the iptables DROP bucket, and take it out when the ban timer expires? Again, I'd vastly prefer a solution that uses as much software available in Debian as possible, though I can build Debian packages in a pinch.

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  • World Wide Publishing Service very slow to restart on IIS? Why?

    - by StacMan
    Every now and then, we look to restart our IIS server by restarting the "WWW Publishing Service". On most systems this would usually only take a minute or two, but this can often take up to 10 minutes to stop the server and restart. Does anyone know any way to work out what is taking so much time to stop the service? After reading up around the net I've learned this may be due to locked resources used by users and/or lower-level IIS cached items being recycled. But I cant seem to work out where I can validate if this is true on not. Also if anyone knows how to fix or speed this up, that would be excellent. We have a large codebase which contains over 280 aspx pages across the site. Our main domain contains about 100 aspx pages whilst the subdomains contain 15 or 20 each. Some specs: Code is written in C#; runs on .Net framework 2.0 Server Windows Web Server 2008 IIS7; DB running SQL Server 2008 Standard

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  • Why does my Internet slow to a crawl unless I reboot my router every few days?

    - by Lord Torgamus
    A few weeks ago, I noticed that my Internet connection had slowed down to a crawl. I waited a few days hoping it would go away on its own, but it didn't get better. So I asked this question about how to make it faster. The problem went away after I updated to the latest firmware, so I didn't follow up too carefully. But every few days since then, my Internet has slowed down again. Unlike before, all I have to do to fix it is open the router administration page and press the "Reboot" button. Nothing else seems to work, though I'm sure there are options I haven't tried. If it makes a difference, my girlfriend and I both transfer large amounts of data fairly routinely for school (videoconferencing, downloading entire recorded lectures). The router is a Cisco/Linksys 160N V3 that's about a year old. Most of the time, it deals with just two standard Windows 7 laptops. The only thing I came across while searching for answers/dupes was this question, which seems similar superficially, but probably doesn't have the same root issue. Anyways, it's not resolved. What could be causing these slowdowns, and how can I get rid of them?

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  • apache2 and php slow first load on Ubuntu VPS - something like mysqltuner but for apache?

    - by talkingnews
    Ubuntu 10.10 64 bit VPS, 512Mb dedicated RAM. Mysql tuned so that sqltuner is completely happy. Used RAM never above 350Mb out of the 493 available. Load never exceeds 1.04 or so. httpd.conf tuned as per all the guides for vps of that memory - amount of preforks, spares etc. But for the FIRST load a site after having not visited for a while, it's taking ages. First load: Parse Time: 3.576 - Number of Queries: 50 - Query Time: 0.019723195953369 Reload Parse Time: 0.096 - Number of Queries: 39 - Query Time: 0.0066126374511719 Subsequent reloads will be at this speed. htop shows two items as soon as I load that page for the first time: php-cgi /usr/sbin/apache2 -k start I'm using suPHP but I've tried fast-cgi and cgi. Stuck now, a weekend of tweaking has brought me nothing. Advice appreciated.

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  • Is VirtualBox really slow compared to the host OS? (for Ruby development)

    - by dan
    I have VirtualBox running Ubuntu as a guest environment on my Macbook Pro running Leopard OS X 10.5. I timed the same batch of Ruby on Rails unit tests on both systems. The difference seems to be quite big. The same suite of Ruby unit tests that take 13.4 seconds in the native OS X, take 82 seconds to run in VirtualBox Ubuntu. Are other people doing the same kind of development noticing the same differences?

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  • Why is SMB from a Windows 7 64-bit to OS X Server so slow when using DNS vs IP?

    - by chuboy
    When I connect my 64-bit Windows 7 to a OS X server using \servername, my transfer rates are around 400KB/s. However, when I do the same thing using \192.168.0.10 (which is the IP of the server), transfer rates jump to 30MB/s. All of this happens via a gigabit ethernet cable with my wireless disabled I heard Samba itself "doesn't use DNS", but if that's the case, how am I able to connect to the server in the first place?

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  • Reimage PC: Myth or Fact to speeding up a slow PC?

    - by sunpech
    I have a 4-5 year old PC running Windows XP for software development at work. It struggles to run all development tools I need at the same time. Management feels I need to reimage my computer to "speed it up". The last time it was imaged was about 3 years ago. What resources books, websites, blogs, articles, etc are out there that supports/debunks this well known belief that reimaging an old PC running Windows XP will make it faster once again? A resource I remember reading is from Lifehacker.com: Windows Maintenance Tips: The Good, Bad And Useless

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  • Database server: Small quick RAM or large slow RAM?

    - by Josh Smeaton
    We are currently designing our new database servers, and have come up with a trade off I'm not entirely sure of how to answer. These are our options: 48GB 1333MHz, or 96GB 1066MHz. My thinking is that RAM should be plentiful for a Database Server (we have plenty and plenty of data, and some very large queries) rather than as quick as it could be. Apparently we can't get 16GB chips at 1333MHz, hence the choices above. So, should we get lots of slower RAM, or less faster RAM? Extra Info: Number of DIMM Slots Available: 6 Servers: Dell Blades CPU: 6 core (only single socket due to Oracle licensing).

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  • 256 SSD / 2TB Internal drive, i7, 16GB RAM.. explorer.exe still slow

    - by web_dvlp_sd
    OK, so I just got done tweaking my brand new PC and explorer.exe still manages to be sluggish not as snappy as I'd like or expected at all. Specs are i7 4th gen processor, 16GB RAM, windows 7 64 home premium on 256GB SSD, secondary internal 2TB drive. I assumed system would be lightning fast, been doing a bunch of researching and switched out a lot of different settings including enabling/disabling indexing, turning pagefile on/off or placing it on separate drive, turning folder optimization options on/off.. changes have been minimal or none at all. Any further advice or anything I might be missing, besides a new/repair install? PC is literally 3 days old I don't feel like I need a new install at all

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  • Does AMD Cool n Quiet Slow Down Your System?

    - by Software Monkey
    I discovered today that having AMD Cool n Quiet enabled in my BIOS appears to be slowing down my Windows XP SP2 system by about 29% on memory & CPU intensive workloads. I was wondering if (a) anyone else had encountered this, (b) anyone can offer an explanation, (c) there are any negatives I need to be aware of if I keep AMD CnQ disabled. With some superficial testing so far, I don't immediately notice any difference with CnQ off (other than the performance being what I expected from this new hardware). It seems to ramp up the CPU fan a little bit as my program maxes out 1 core, but that's the same as with CnQ on. And when I let the system idle the CPU fan slows down and the systems as quiet as a mouse (after years of 6 small fans churning like they want to go into orbit it's nice to again have a system where I can hear the HDDs seeking). Bonus question: Does CnQ cause issues with system stability? I ask because the reason I disabled it was because I have had a few freezes and 1 spontaneous reboot with my new hardware.

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  • Can many addon domains slow down cPanel or create problems?

    - by Marco Demaio
    I actually resell hosting plans by using one single cPanel account and many addon domains under it. Basically for each new user I don't create a new cP account, but I simply create a new ADDON domain and give him the necessary space. I know in this way the final user won't be able to manage his emails and he won't be able to access all cPanel features, but that's ok. I know in my account I'm allowed to add unlimited addon domains, but adding many addon domains is there something that might happen that slows down cPanel or could create problems? Any suggestions you could give me about the way i'm using cPanel which might not be the usual way of using it. (As for instance: "be aware that mails from different addon domains under the same CP account could create many problems.", etc.) Thanks!

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  • Picasa v.3.6.2 for Mac is suddenly very slow - what are the implications of rebuilding my database?

    - by 3rdparty
    Recently Picasa v3.6.2 for Mac has become very sluggish - mainly noticable for any (non destructive) changes made to photos such as starring an image. This action used to be nearly immediate, but recently I've found it can take 1-3 seconds for Picasa to register the change, and become responsive again. I'm considering rebuilding my Picasa database as per these instructions - however I'm concerned I may lose any pre-existing non-destructive (unsaved) edits, along with Picasa albums that I have created. Curious if anyone has experienced Picasa sluggishness with the latest version and/or what their results have been from rebuilding their database. My last resort is to SuperDuper my drive and then rebuild the database, so I can always restore it if I lose critical data.

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  • Very Large number of connections in TIME_WAIT state; Server is slow, ipconntrac

    - by Sparsh Gupta
    I have a nginx server with load balancing and reverse proxy. Right now its behing another nginx but very soon I plan to make it front, where it will receive TCP connections from clients directly at a rate of 500req/second I am having some big troubles with the server. I have pasted my configurations here and I am kinda sure that the problem is with ipconntrac and similar things which are alient to me http://paste.org/pastebin/view/28543 root@load_balancer:/proc/sys/net/ipv4# netstat -an|awk '/tcp/ {print $6}'|sort|uniq -c 67 CLOSING 727 ESTABLISHED 173 FIN_WAIT1 183 FIN_WAIT2 19 LAST_ACK 5 LISTEN 447 SYN_RECV 1 SYN_SENT 27970 TIME_WAIT Its a ubuntu machine with mainly nginx (load balancer and reverse proxy) installed. It surely isnt great. Can you help me understand whats going on and how can I fix it. This is my live server and I am sure its in a bad shape right now. Any document or commands to fix this, or settings I should make to make this better and reduce time wait and fin_wait1/2 better would be awesome.

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